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The family of a 19-year-old Marine decided to take him off life support after he was found shot in a car in South Los Angeles. Marin Austin reports for the NBC4 News at 11 p.m. on Monday, Sept. 19, 2016. (Published Tuesday, Sept. 20, 2016)

A 19-year-old Marine who was known for his generosity and spending his free time helping others died Monday, three days after he was found shot in a car in South Los Angeles.

A coroner official confirmed that Lance Corporal Carlos Segovia died Monday night.

Segovia was found with a single gunshot to the head late Friday in a Dodge Charger in the 2100 block of 31st Street, according to the Los Angeles Police Department. Family members told NBC4 Southern California he was in grave condition. Doctors said his wound was irreversible.

"This is a big loss to the USA," said mother Sandra Lopez. "A big loss."

No arrests were reported.

"At this point, it's absolutely a mystery," LAPD Capt. Peter Whittingham told the Los Angeles Times. "Like so many cases in South L.A., we have nothing to go on at this point."

Segovia was on leave from Camp Pendleton near San Diego and visiting family and friends in Los Angeles. He left the base Friday and was struck by gunfire later that night after leaving the home of girlfriend's parents, family members said.

Neighbor Walter Baldwin came out when he heard a noise and was sickened by what he saw.

"He was slumped over the steering wheel with nothing but blood on him," he said.

Mystery Surrounds Case of Marine Shot in Car

Family and friends say a 19-year-old Marine had no enemies and used his free time to help others. Patrick Healy reports for the NBC4 News at 11 a.m. on Monday Sept. 19, 2016.

(Published Monday, Sept. 19, 2016)

Segovia was not in uniform during the shooting, The Associated Press reported. He was found slumped over in the driver's seat of the car, shot in the head, and was unlikely to survive, officials said.

He joined the Marines about six months ago after finishing high school. His mother said he became a Marine so he could offer even more to his community and the country.

"He was a giving person," Lopez said. "He became a Marine because that wasn't enough, what he was doing for the community."